What are flaky and elongated aggregates? How can the shape of aggregate influence strength of concrete? Following is the result of a sieve analysis of 500 gm aggregate:
|IS sieve size||10 mm||4.75 mm||2·36 mm||1·18 mm||600 micron||300 micron||150 micron||lower than 150 micron|
|Weight retained in gm||0||10||50||50||95||175||85||35|
Find out the 'Fineness Modulus' of the sample
FLAKY AGGREGATES:- This agg. Are those whose least dimension i.e. thickness is less than 3/5 th of their mean dimension.
ELONGATED AGGREGATES:- This agg. are those whose greater dimension i.e. length is greater than 9/5 th of their mean dimension.
According to shape voids
Rounded aggregate 32 – 33 %
Irregular aggregate 35 – 38 %
Angular aggregate 38 – 40 %
Rounded aggregate gives better workability and Angular aggregate gives better strength.
total wt. = 500gm.
|Sieve||Wt. retained in each sieve(gm)||% wt. retained||cumulative % of wt. retained||% finer|
|Ƹ = 346|
So, F.M. = 346/100 = 3.46
F.M. of coarse aggregate is3.46.
Give the physical characteristics of 53 grade OPC.
Discuss the role of Gel-space ratio. How can it be determined? Calculate the gel-space ratio and theoretical strength of a sample of concrete made with 500gm of cement with 0.5 w/c ratio on full hydration and 40% partial hydration. Discuss the factors which influence creep in concrete?
Differentiate between creep and shrinkage of concrete.
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